High temperature oxidation resistance of hot-pressed h-BN/ZrO2 composites

Influences of ZrO 2 additive on the microstructure and high temperature oxidation behavior of h-BN/ZrO 2 composites have been investigated. In addition to the enhanced strength , the oxidation reaction between boron and oxygen can be effectively hindered even at 1200   °C when adding 20   wt% ZrO 2 into the h-BN matrix. Besides the doped ZrO 2 particles, ZrB 2 and ZrB were also formed in the composites after sintering via the reaction between ZrO 2 and h-BN. The oxidation product ZrO 2 of these Zr–B compounds can act as protective layer during oxidation, which covers the sample surface and prevents further penetration of oxygen. Good oxidation resistance at 1200   °C and high strength make h-BN/ZrO 2 composites promising materials for high temperature applications.